<?php
class SoybeanCondiment extends Condiment
{
    protected $coffee;
    protected $description;
    protected $pay;
    public function __construct(Coffee $coffee)
    {
        $this->coffee       = $coffee;
        $this->description  = '豆浆';
        $this->pay         = 2;
    }

    public function getDescription()
    {
        return $this->coffee->getDescription() . $this->description;
    }

    public function cost()
    {
        return $this->pay + $this->coffee->cost();
    }
}